Therapeutic exercise devices utilizing reciprocating ankle rests are known. In use, a person will lie flat on his back and place his ankles on the ankle rest. In operation, the ankle rest reciprocates horizontally in a side-to-side motion which causes the legs to swing back and forth. During this time, a person's legs are suspended above the floor or surface on which the person is resting such that the back of the knee is not supported by the exercise device. Improvements are desired.